Telephone system.



W. L. CAMPBELL.

TELEPHONE SYSTEM.

APPLICATION FILED 001.1. 1901.

for:

lalal \m W. L. CAMPBELL.

TELEPHGNE SYSTEM.

APPUCATLON FILED OCT. 1901. l ,267,743. Patented May 28,1918.

4 SHEETS-SHEET 2.

G? L naamw A fa??? W. L. CAMPBELL.

TELEPHONE SYSTEM.

APPucArmN FILED ocr. 7. 1901.

Patented May 28, 1918.

4 SHEETSSHEET 3.

71, zo 21": /ff

W. L. CAMPBELL.

TELEPHONE SYSTEM.

APPLlcmoN mw om. r. 19o?.

Patented May 28, 1918.

UNTTED STATES PATENT OFFICE.

WILSON L. CAMPBELL, 0F LA. GRANGE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 AUTOMATIC ELECTRIC COMPANY, A CORPORATION 0F ILLINOIS.

TELEPHONE SYSTEM.

Application filed October 7, 1907.

To all whom, it muy concern.'

Be it known that I, W iLsoNL. CAMPBELL, a citizen oi the United States of America, and resident of La. Grange, Cook county Illinois, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems in general, but more particularly to systems in which automatic. service is provided between the subscribersof the system, either in whole or in part, and more especially to systems in which main and subrcnlral stations or exchanges are employed, with provisions for giving service between subscribers ot' the main station and the subscribers of a branch or Sub-central station. Generally stated, therefore, the object` of my invention is the provision of an improved and highly efiicient telephone eX- change system.

Special objects are the provision of an improved arrangement by which the sub scribers of a branch exchange may be given service between themselves Without the necessity of calling through the main or central station, and whereby efficient service may also be insured between the subscribers of the main exchangeand the subscribers of the branch or sub-central station; the provision of automatic switches, such` tor example, as connectors, whie are adapted for use in automatically establishing connection between subscribers lines of the branch exchange, as Well as for automatically establishing trunk connection to the main or centralv station, said connectors each having provisions for automatically rotating` in one or more of the bank levels thereof, whereby each connector is adapted for both selecting idle trunk-lines and making the final connections with the lines of the called subscribers; the provision of means whereby the subscribers of a branch exchange or sub-central station may intcrcommunicatr through the medium of individual trunhing; switches and connectors, without the necessity of employing any selectors or other automatic switches bctween said line switches and connectors, whereby each of said' connectors is adapted to give service of this kind only in certain bank levels thereof, the remaining level or Specification of Letters Patent.

Patented May 28, 1918.

serial No. 396,230.

levels being appropriated exclusively for use in giving automatic trunking service to the main or central station; the provision of automatic connectors which are adapted to make connection directly with the lines of called subscribers, and which are also adapted to automatically select idle trunks terminating at a manual switchboard; the provision of improved means whereby any trunking connections established through these connectors may be efficiently supervised by the operators at the manual switchboards; the provision of means for preventing connectors which are connected directly' with non-numerical or individual trunking switches from releasingr the latter when the called subscribers lines are busy; the provision of means for supplying talking eurrcr through these connectors, which are rotary or automatic trunkselecting in ,one level only, to calling and called automatic subscribers, and separate means tor supplying talking current to called manual subscribers; and the provision of certain details and features of improvement and combinations tendingr to increase the general efficieney and serviceability of ,a telephone eX'- change system of', this particular character.

To the foregoing and other useful ends,

my invention consists in matters hereimitter` set forth and claimed.

In the accompanying drawings Figure 1 represents diagrammntically two substations A and A ot' a sub-exchange connected together through the medium of my improved switching apparatus, in a system embodying the principles of my invention. At C is shown diagrammatically an individual switch allotted to the line of substation A, and at D is represented the master switch allotted to the group of which C is a member. At E is shown my improved connector switch, and at C' is represented the line switch allotted to the line of the substation A. The common battery B is shown having its positive terminal preferably grounded.

In Fig. 2 is represented the main or manual telephone exchange equipment of the said system.

Fig. 3 ls a diagrammatic perspective view of my improved connector switch.

In Fig. 4 is shown diagrammatically the line switch C and its master switch D manna net 40 is energa'zed by a preliminary impulse as the subscriber starts to call, and the armature 48 is attracted against the magnet cores. When the armature 43 is attracted to the left (Fig. 4) the catch 48 slides out of contact with the end 49 of the plunger arm 38, and the said plungeiI arm, owing to the tension of the spring 50, moves about the pin 4G and thrusts the plunger 37into the bank terminal Q; and when the trip magnet a ain denergizes, the trip armature 43 alle against the end of the plunger arm 38. The switch is restored to normal when the release magnet yall becomes energized, whereby the armature Lil is attrarted, and accordingly the trip armature 43 is moved upwardly, compressing the spring 50 until the catch 18 slides over the end 49,' then when the release magnet fil becomes denergized the armature 41 returns to normal position against the stop 47 by the action of the spring 50, since the trip armature 43 is now locked at the catch 48 with the plunger arm 258 ai the end 479. Thus, when the plunger arm 38 is unlocked the spring 50 forces the plunger 37 into the bank, but when the three arms 3H, il and 43 are locked the spring 50 tends to force the combined parts down against the stop 47, withdrawing the plunger 37,l and since the plunger arm 3S is now in engagement with the armature 43, the said plunger arm is moved about the pin 46, whereby tlleplungcr 537 is removed from the bank Q. Also, since the plunger shaft has advanced one step, the huh 5l otthe plunger 37 comes to rest in the position shown by the dotted lines in Fig. et, against the plunger shaft 52; and as the said plunger shaft advances each time an. idle trunk is seized, the plunger 37 is not advanced, but remains opposite the trunk terminal from which it has just disengaged, since the slot 53 is not in engagement with the plunger shaft 52. After all of the trunk-lines have been successively seized` and the plunger shaft again passes to the position it occupied when the plun lfer 3T seized the terminal Q, the plunger 3 then returns to normal engagement with the said plunger shaft. ln the meantime, if the line switch C is agaiii operated, the plunger 3.7 again engages the same terminal Q. The said line switch is provided with a bank of terminals, usually ten in number, only one ot which is shown at Q (Fig. 4), As shown in Fig. 4 the said terminal is turned from its true position with respect to the swing of the plunger 87, and the bushing 54 is also shown turned. correspondingly1` all for the purpose of making the illustration clearer. The terminal comprises the springs 55 and 56, 57 and 58, 59 and 60, and 61 and 62. The said springs are normally disconnected from cach other, but are driven into contact in the above-mentioned order when the plunger `37 operates. .Howevem the plunger 37 is normally retained in engagement with the plunger-controlling shaft 52, which latter 1s operated by the master swltch D. The master switch D, which may be ol any suitable or approved type, is provided for operating the plunger shaft 52, and, for eentrolling certain circuits that will be disclosed hereinafter. Said switch comprises the following details: A.' motor magnet (53 for operating the ratchet wheel (Si, which latter is designed lor operating the plunger shaft .52, and a differential relay (i5 for controlling the energizing circuit of the motor magnet (i3. The said master switch also has a bank comprising a plurality of `individual contact segments a and a common segment 66, as shown in Fig. 4. The wiper 67 is adapted to ren'iain in constant engagement with the bank O, and to at all times maintain some one of the segments ein electric connection with the commen segment 66, cxcept during its backward movement. The wiper (i7 is operated in a stcp-bystep manner by the ratchet wheel 6l, through the medium of a cam member GS rigidly secured to the said wiper G7 and adapted to successively engage the pins G9, 70, 71 and 72 upon the said ratchet wheel Gl. The motor magnet G3 is provided with` au armature 73 upon the end of which there is suitably se-. cured a pawl 74. Each time that the said magnet is energized the pawl 7-1 engages the ratchet wheel 64, advancing the latter one step. It will be seen, therefore, that as the ratchet wheel 64 advances, the wiper 67 advances step by step from right to left, and when the piu G9, for instance, clears the cam 68 the retracting spring 75 restores the wiper 67 to its lirst position at the right of the bank and in engagement with the first segment 76. The said` motor magnet (i3 is provided with a couple of interrupter springs 77 and 78 that are included in the energizing Circuit of th(` said motor magnet, which energizing circuit also comprises the springs 79 and 80 controlled by the diHerential relay 65. Therefore, whenever the differential relay 65 is energized, the springs 79 and 80 are pressed into contact, and the motor magnet (33 operates stepI by step as long as the differential relay G5 remains energized. Furthermore. it is assumed that the terminal Q ot' the line switch C is the first terminal of the line switch bank. The plunger El?, while in normal engagement with the shaft 52, is retained in front of said terminal b v the plunger shaft 52 whenever the master switch wiper (37 is in engagement with the bank segment 7G; but as the' motor magnet 63 advances the wiper (i7 onto the segment 81, the said plunger and all idle piangi-rs similarly engaging the shaft are carried opposite the next terminal of the line switch bank. Furthern'iore, an auxil inry reifjf i152 is lnforidml for opening the rimini through the trip muguet 40, so than, xho iino swiirh C rmmot be operated while (he nniior 'magnet U3 is energized. The .lo r relay 'i252 heilig ronneuteii in Series with lll or magnet relay fn anni iinnlon-n fri or', heini: operatori lo the ri in) 13T, l is. oridenl Lhol ail ihrer. wili ho ener'- gixml zit the :Jr-1. iinie.y ille rehry '1531! lino-1 .Shilling 1hr 1.0- i': 1 i vvilh ihexprlog in eorh iine lan. li lmnh :il oi' lhe Sgn ing fr? :ire per1rmnonri}l ronnwwl unil mm hi: umile o l' one common pier-e. The spring-s Fill, 'hrnwrviz are inilimhml nlimi there i;

one Helma-@ite und lioiiml :giving i'o: over): lgzinl, srl. (L there lwoo,l "on in tin. hunk. The onlin@ 5T. To', lli! xml V-i. hlm tho trunk-line r'oinnrisine ihr roniln'isiors r'. Si! .nini Si loiniinjgj to thironneeior ixmhr. 'l h4n snhseribei-eline eoncllivior#v 2U anni Si.) termi note in [he springs sind 5T which, w, im@` been blzitefh nre emnnnnl prings. 'When the snbboriller operarios ihr line switch (f. om! ihr plunger 37 engages The. terminal Q., the suheorihofs lino ermdlwtors 129 and 30 are ex tended to the vertical and rotary crunk eomhlriors 82 u od S3. thence to the switrh E,

The connector Snitch F is. :in iinlfiroreri '.lorin of the eonneeior Switeh deoerilleil in Uniiefl States Potrai-t No. ii.l'. .g'rnoieii March 13, 1906, (,o Keilh. Erirhson i\`; lilrh'hoon. For instance, the Connector swiirh :shaft S9 Carries the line wipers 90 and 91 and the private wiper 9i. 4The cornieetor swileh is also fontroiled by the culling subscriber through ihe ineiiinln of iho .'ortieui and. voilier ihre reihig JS anni f-I. The. Tol'- Liffai lino rising" "93 riirizeiiy conti-oh the` vertrioul magnet Ji inni also the rotary magnet The purpose of the Vertical magnet 95 is to give the Slmft :1nd shaft wipers o reriicui motion@ :nirfidho rotary magnet; 9C iinfmris to the shaft sind Shaft, wipers o rotary or circular motion. The rolory ,line relay 94 eont'rois the private magnet, 9T. vfhieh latter under ceri-nin conditions; conlroh7 in turn the vel-tirol :mii rotary n'mgrneh-J J5 oni 96; the release magnet. 98, und. also Ihr sirio switch wipers 99, 100, 10i` 102 :nld io, which comprise the weil-himno side. 1 s\\.i1.eh. The, Said sido switch hos; n. norm-.1i or 11nd position, :i second position '.1 nd a third posi-` Lion. The release magnet JS is oleo roo irolieil hy the verticali :mii rotary ii'ne relaxe 9? :uni 9i eonjointly. By the use. of the eoniionsers 101. und iho connector divides the circuiti through it vinto two seviiims. The connector is provided with :i dili'rrro- *,iaiiy-wouml relay 10U which ie composed of tenth level of the ronoeeor honk.

the windings 107 and 108. The purpose of ihis relay is to provide the ealling subscriber with talking buttery current when the bachllrir'lge relay 109 energizes, und uism hy menne of the verti ml line relay U25, (o con trol (he ringer relay il() by which the ringer generator H is bridged across the terminals of the called line to signal the called Sno iher. The baekbridgo relay 109. coinprising the windinge 11.1 and 11i?, prow-idw` llo; milled subscriber with talking' imiter) rnrrenl when the prinniry circuit ot' thi- .illro nhslu'lioo is: bridged across thi` iiw 'lloroll-:1l :Jurion is eqnippmi with 1h .il wili lio ohaerx m; switch hm O liy wir :lu-slur oilmeni.. ."enffwij. the .magnet (33. '-liu fmnert1 r w. itwi l, im fit ioziei two motor flrnionis. noiwir i r tieni magnet l??? it il. The romy innw.- if.. AS hilo :xlrmiiji heen explrime-'ql vh;- inzignoi, 35 is for lansing ihr sahsil v ii'ie magnet 96 is for roizitiing ihr -;lm`r.

.i leerer undersetzuniinpj oi" iin oprit-'oan of in v improved .Qyn'rni may hr om: me'. or considering its notion when one wiwgifilfler @AHS :'enoiher. Assume.. im" nxmnilin, ii'oif the siihbrrilwr at r11. tation More io mili some millsrrilvo ai. enimioiiwi .ir-1 whieh niloirl io :he mnnuafi enchainer re'lnersentoii in i-igi'. As previously explained, ihr ironic-hoes 4from the aiilonmic rentra i olir-o io the inchino] eenrrnl oiiiee imei from the Hence, when n. monooi exch 93e frmfoection is 11eireil lo' on :nominatie mii-.hum wiileeroer [he anroimlie .Cnhgfri er r.--l`. i r; @Might on hie iiiui. To v-.uii nnlgihi ihr enlwrriinr nl; suhslziition i operates he euiiingf device in the Ymiifirnmn manner. voro oooiiwf in 1hr elogi?. lhiirv'io il. iiioiinl, 'i' loep l' .U i ior orrriiiifig; im Sw w E. L. munir: vom

Vi lli;

ll j il 1 ,ill

the calling subscriber rotates the. dial forward, whereby the rotary impulsey spring 2;) is momentarily pressed against the ground post 16. As a result, the trip magnet 39 of the line switch (l is energized by a How of current troni groulnl (i to the springs 1l and 13. ground post 16. rotary impulse spring4 'if to the rotar line conductor 30, eouductor 12? (Fig, it), bridgecut-otl' relay springs 1:21, 125 and 126 to the trip magnet 4t), thence through the said magnet to the eoinluctor 127, springs 12S and 129 to the battery lead i230. and thence through batlery l to ground (l. As soon as the trip man-net l0 enel-glues, then the armature '13 is attracted and the plunger 37 is liberated and thrust into the terminal Q by a spring 5U. When the plunger 37 engages the bank terniinal Q, an energizing circuit is closed through the niotor magnet relay 6ft, which in turn operates to close a circuit tlnrough the. motor magnet 63. The lnotor magnet operates to place. the idle pl angers opposite the first idle bank terminal similar to the teriniual Q. The circuit through the relay 65 extends from ground (l2 through the windingr 131 of the relay 65, thence through the auxiliary relay 182, segment 66, wiper arni Il?, segment 76, conductor 135, bank springs tf. and lli. llirongh the release magnet 41 to the battery lead 130, thence through battery l to ground G. Although this circuit includes the release magnet 4l. the said maguet does not operatively energize, since the relay f3.3 is wound to a high resistance, while the winding;y of the release magnet is ot' a comparatively low resistance. The relay 65, upon energizinf. operates to close the springs 79 and Si) in Contact, whereby a cireuit is completed through the motor inagnet (5:3 exteniiling from ground G3 through the springs ell and Tt), nlotor magnet 321. springs TS and 7T to the battery lead lltl, thence. through battery B to ground (l. The motor nmgnet 63%, upon energizing. attracts its armature 7 u, whereby the pawl 7l engages the ratchet Wheel 64 and rotates the said wheel one step. lfVhen the armature 73 is attracted against the mag'- net cores, the springs 77 and 78 disengage, thereby breaking the energizing circuit through the motor magnet. The cam-arm (38, being in engagement with the pin 69, is operated to advance the plunger shaft 52 (and, consequently, all idle plungers that may be in normal position) one step to another bank terminal. Also, the wiper 67 is carried from the contact pointy 76, which corresponds to the terminal Q, to the contact point H1. which latter corresponds to the ter minal before which the advanced Idle plungers are now resting. At the instant that the plunger 37 enters the bank ternunal Q, the following springs are pressed into contact: 55 and 56, 57 and 58, 59 and 60, and 61 and 62. The engagement of the springs 5b and 60 establishes a circuit from ground G, by Way of the normal conductor 87, to the connector private bank contacts correspond ing to the line that terminates in the line switch C, whereby a guarding potential is established to prevent any subscriber troni calling the said line after the calling subscriber at substation A operates his dial preparatory to nia king' a call, as explained. The circuit over which the said guarding potential is established extends l rol n ground l* through the haul; springs 59 and 6() to the private normal conductor S7, thence to thc connector private bank. The engagement of the springs 59 and 60 also closes a circuit through the bridge-cut-olf relay 39, said circuit eX- teuding from ground G* through the springs 5t) and 60, conductor 134, through the relay to the battery lead 130, thence through battery B to ground Gr. The said relay, upon energizing, breaks the Contact between the springs 121, 125 and 126, whereby the vertical and rotary line conductors 29 and 30 are disconnected from the trip magnet 40. The closure of connection between the springs 61 and 62 establishes a guarding potential at the master switch bank contact 76 over the following circuit: from battery B to the bat tery lead 130, thence through the. release magnet 11 and springs 61 and 62, conductor 133 to the said Contact point 76. It will be understood that the bank terminal Q, beingl the first bank terminal of the line switch bank, corresponds to the first segment 76 of 100 the master switch bank t). This guarding potential protects the Seized trunk conductors S3 and 8l from being seized by other plunger-s. Suppose that the master switch has operated and carried the Wiper 105 67 to the last contact,` point i135. Now, when the motor magnet operates for the lrst step, the wiper 67 engages the contact point To, at. which there, is a guarding potential, and an energizing circuit is established 110 through the differential relay 65, which in turn operates to close an energizing circuit through the motor magnet 63. The current through the said relay Hows frein thc said contact T6 through the wiper 67 to the com 115 :non segment 66, relay 132, through the winding 131 of the differential relay 65 to ground G. lhen the differential relay 65 attracts its armature the differential relay springs 7S) and 80 are pressed into contact, 120 thereby closing an energizing circuit for the inotor magnet 63 from ground G3 through the said springs 80 and 79, through the Inotor magnet. 63, springs 78 and 77, thence to the battery lead 130, and through battery B 125 to ground G. The motor magnet then 0perates, as previously explained, to rotate the ratchet wheel 64 one step for advancing the plunger shaft 53 fone step, and the master switch wiper 67 one step also and into en- 130 uuoonir r. ls in www! @rnrwn thun :ulmnuml om: liep ibo plm n carrirs all idle plnngors tbm uri: ne ongngi nient, willi ilw said plelngai `uba l1 to a poing opposite #no nm'l bunk t'frininzil, is ax- Jfilmini-1. 1f rhone .llonlll bo n guarding pntontinl at tlm bunk augment nl o1' lbf:- 11i-stur switch bank ibo llillrrmitinl rolnfy lij will r Y nmin onorgizcfl, wlurrbf, tibo onorgizn @uit through tbe Inomr magnet 325 is urun completed 'wbon the motor magnet @rings T7 und 78 again engage; unil :is :1 result, tlm motor nagnr n3 ugfin ol'ierruucl. when by tbe plunger shaft :nul nis-alor :oriob wiper (3T ure advanced nolfbcr sion This operation nontinues as long as tbv wipifr l' contilnlm to iinl rsogxnon@ with grani-lling potent lub A mon as ssn idlr .Se-grown ia found, bon'm'vr, mln! onorgzing circuit bronglz tlm dill'ol'entiufl relay G5 in brolioln al; whirl; inno tlm said rielnjf in turn breaks be rirwrgining.; oir-cuit for ibo motor nmgne. H until llna nord slabooribrr xnuko- :1 call. '1bn olosirr-i of connerion betwoun tbl` springs nii il S16 o ronds flu: culling subscriber-14 rertbnl uonducto-r to tbn rurticnl Lrlnll; onlinr-mr 81.*, which latter lL-zul; to tbc oonnvnior r'ertianl lin@r relay 93. Tb@ closure olf @omdat bntWr-n tbe springs 5T and 56 @tonda iliono .scribirs rotary lino condntor l? lo tin rolury trunk conductor S3, wbioi biliar lenfln to ibo connector rotary line rvlny lll. "bo :subscriber ut. substalion A lun; ibm; Yrealm lished connection will tibo oournzrlor 1i? nml now when lb@ llinl rolnrns rowuz'i nominal position, thus grounding ibo xrrirzsi bnn conductor E59 euch inio ilmL the inl El spring ill prossoil ono lin; ground pour 16, tho wrtical lino relay U3 ol ibo Column-or lil is ennrgized by u ilorf of uni-runt from 1bn substation ground G; und irnlnodnlrolg br:- loro tlm dial stops, tbe impulso to Lina ronry linocomlnctor llonvrgizcsllm connector roturv line, relay 91- nlso. The cn'fuit through thep vertical lino rel-njy U25 extends from the ground G through tbe spring 11 und lo tbe ground post 1G, thence, through lin: uni pulso Spring 21 to tbe vertical line uonrluolor Zinlino swcb. bunk springs (153.11111 llh vortionl trunk lino Conductor n2, wr mi! lino n lay 13 Winding 1U@` of ibo ilurvntinl rol-Ly 101'. conductor 136 to the both-ry lvznl 1230, thence through l'azxtlury il in ground G. Euch time that the vertical lino relay 93 rn` orgizes ille relay pring 13T in prosnod onto tbe ground spring 138. Tho vfrtiral magnet is thereby onergmefl and the. wiporsx 90, 51 and 492 of the connector are raised one, step at a time-to tbe tenth bank level :unl brought, opposite the first Contact of tbe Suid level. The energizing circuit, of the said nmgnotextends from ground G5 through the springs 138 and 137 to the conductor 1353 privare magnet springs 140 and 141, conductor 112, side. switch wiper; 102, ccf-nmol nennt 14:21

lor 'rfihfb rmnlw-i lu tfrntb lovol s :nl n colector .Lnrirlzw tlm. is, it ro l u ziixloniuliraily lo fnn in iiliif innlr lino in mili lvnlb invul. Ul courriel, ibis autoomlo roaton is iniifalud when the rotnry impulse transmitted by lb@ backward .rotation o 'b') onllillg rlinl l1 is lo be notml that in this lenh lowl tbe: first Lm of Gmb ms is not naomi for :1 trunk-line. As sbown in Fig; 3, the rr'll prmln lmnlf contact 5217 is; gronnilufl prrrnnnontly` t n objvr being to prox-idinf f, by n'bicb tin" snlr milch muy bo 'rigiy f irri lim-:nino allor [1.o swilvii E i! lo lbr lof il point 11i-Will urn will norm' 51 op on tho herum-f oi lb, ground on lin; giri l :ibo rgnnnnl. 211'; bnli if tbv. wond ser, o'. oonlnln; :S nilo tbc baffi will liv rolnod unlil l'bo i. ig is zarilvo on lbosi contacts. 1f lulu Second srt; of .:onmols ln1 1y--tlmt im if flan l'rfzt :roule lino to tbv manual @Xchange is buoy-tbn @mmf-artnr will automatically ron "o until Lire wig; ra nre; ,-nrriml onto 1bn bicl al of nominare, or fin-t varon-tl trunk 1lb-:il loznlor to ilir nnennzil oxidizing@ nnrfl so on. '11m :imonnmc roalon in bri'mglil about as follows: when ibr Spring 119.1. lll and. 121 oro broug'bi; into nonfarm. :is llo: 5h11!!` H 'Vrnflnm flu fi Ui bruni, ne prmionsly ox iuinmlq Nin rom`- ningnoli *.113 :is woll :is ibo auxiliary wbr; l E are zinnillunvoily ron-- novlml vitb 1111@ Hnlf- Switch Contact point '15?. l? lis wrlicnl [imA relay 43 opernrs o r rA bi1 sn'iul. haft nl?" lo tbe tvntb level l'zrongrb ibo fondono ol' tbn vortirnl magnet Y. n, :ilnunl oxplzxinufll` t'lnfn wlwn ibo ronny imprluo onor-gils 11b@ rotary line 'relay Jlrflw privato magnet 91 is in nrn onergizod and ibo sidi'- Swirb trippril 2.o wooncl jposition. The onnrgzing circuit for fha rolnry line relay extcfnds roln tbe. xniii'tatnn ground f lo Ibo rotary lino ron- Llna'tor .2li/L tlionrif through ibo lineswitch bank sprins 5T and 5S lo the roury trunk oomlnotor 8,5, thenru through thi rotary lino relay Slab and lbrooglx tho winding '108 of tho differential relay 106, through the springs 156 anni in? of the lmolvbrnlge rolay 109 to the battery load 130, tlnnoe through battery B to ground (l. The rotary lino relay, upon energizing, prinses the springs 21S and 138 info contractr whereby an vnvrgzing circuit is closed through lh@ private magnet. 9T. The enrergizng Circuit for said private ningnet 9T extenis from ground (ri through the s rings 138 and 218 to the privato magnet 9i. thence hrougrh the springs 166 and 167 of. the relay l'll to the barbari' load 130, and through battery B to ground i. Thoy privat@ ran-:guet 9T, lipon mnergizing` attracts its armature and releases the side switch from first to second position, at which instant the side switch wiper 103 engages the contact point 1614*l to connect the aforesaid magnets 122 and 96 to ground. Grounding these magnets causes cach of them to energize. The magnet 122 energizes by a HOW of current from ground G to the side switch wiper 103, contact point 14.4, off-normal springs 119 and 120 to the magnet 122, thence to the battery lead 130, and through battery B to ground G. This magnet or relay 122, upon energizing, presses the springs 147 and 149 into contact, whereby the private magnet 97 is put in connection with the side switch contact point 219, which contact 219 is engaged by the side switch Wiper 101, While the side switch is in second position, for extending the said private magnet connection from said contact 219 to the private wiper 92.7 The energizing circuit for the rotary magnet 96, of course, extends from ground G to the side switch wiper 103, side switch contact oint 144, through. the springs 1191201711 '121, und through the interrupterspringsf' to the rotary magnet 96, thenceto the battery lead 130, and through battery B to ground G. The rotary magnet, upon attracting its 3| armature, rotates the shaft 89 one step, earrying the private Wiper 92 onto the grounded contact point 217. As soon as the said Wiper 92 engages the said contact point 217 the private magnet 97 is again energized since, as already explained, the relay 122 is still energized. he energizing circuit for the said private magnet in this case extends from ground G1 to the contact point 217, private Wiper 92, side switch 4o Wiper 101, contact point 219, springs 147 i and 149 to the private magnet 97, thence to the baclebridge relay springs 166 and 167 to the battery lead 130, and through battery B to ground G. The private magnet, upon energizing; attracts its armature and locks the side switch in second` position and maintains the "side switch thus locked as long as the private Wiper 92 is maintained on grounded bank contacts. The side switch '50 being maintained in second position, aft'er the shaft has been rotated one step the rotary magnet 96 is again energized, and as a result the shaft is rotated one more step. If the second private bank contact is not grounded`-that is, if it is not busy-the energizing circuit through the private magnet 97 is broken, and, of course, the side switch isV tripped to third position, at which time the wiper 103 leaves the contact point 144a t0 and prevents the rotary magnet 96 from hecoming energized any more. At the instant that the said side switch passes to third position, the connector side switch Wipers 99 nd 100 having engaged the contact points A1150 and 151, the calling subscribers line :to third position an energizing circuit is closed through the line relay 157 at the manual exchange. This circuit extends from ground G7 t0 `the side switch Winer 101, Winding 112 of the baclebridge relay 109, springs 158 and 159 to the side switch wiper 100, contact point 151, shaft wiper 9], normal conductor 153, trunk conductor 156, through the springs 160 and 161, relay 157, springs 162 and 163. vertical trunk-line con- ,ductor 155, normal conductor 152, shaft Wiper 90, contact point 150, side switch wiper 99, through the winding 111 of the relay 109, springs 161 and 165, throughltho conductor 146 to the battery lead 130, thence through battery B to ground (l. The backbridge relay 109, upon energizing, presses the sprinvV 166 out of engagement with the spring 16'. and into engagement with the spring 168, thus connecting battery B across the line of the calling subscriber, follows: From ground (it, contact point 154. side switch wiper 101, springs 168 and 166, through the winding 108 of the relay 106, rotary line relay 94, trunk conductor 83, line switch springs 58 und 57, rotary line conductor 30, primary Winding 19, transmitter 17, springs 31 and to the vertical line conductor 29, line switch springs 55 and 56, conductor 82, vertical line relay 93. Winding 107 of the relay 106. conductor 146V tothe battery lead 190, thence through battery B to' ground G. The relay 157. upon receiving current, as explained, energizes and draws its armature 169 out of engagement with the Contact point 170 and into engagement with the point 171.\w,hereby a circuit is completed through the line lamp 172. This circuit extends from` ground G1" to the armature 173, contact point 174, springs 175 and 17'6, line lamp 172, contact point 171, armature 169 to the battery B', thence to ground G11. The glowing of the lamp 172 indicated t`o the operator that the trunk-line has been` seized. YAccordingly, the key e is operated' to press 1the springs 178 and 177. 179 and 180 into engagement, and to disengage the springs 175 and 176. By this operation the o erators set o is bridged across the trunk-line conductors 155 and 156 when the said springs engage, and when the springs 175 and 1.76 disengage the rircuit through the line lmnp 172 is broken. Upon learningl that substation A? is desired vl he o crator inserts the plug j into the j ack .l ullottcd to the line of substation A2. `Vhrn the plug p enters the jack J a circuit is closed through the :niporvisory lump 181. This circuit extends from ground (la through the ringr 182 of the jack J, ring 183 ol.' the plug y; to the lump 181, Contact point llll, .firineture 165 to battery B', thence to `ground (in. 'lhe key o is operated to bridge the ringer generator across the line conductors 186 and 1ST of the culled line. ll'lhrn the called subscriber removes tho rouniver 168 from the switch-hook 169 u. eircuit is closed through thi` relays 19() and 191. This circuit extends from ground (in through the relay 161. springs 192 and 193. through the plug' y; to the conzhuftor 18T, switch-hook 185), contact point 191, receiver 166, transmitter conductor 186, through the plusY p, spriiigs 196 and 197'` through the relay 19() to battery B', und thence 'to kfreund (in. This circoli' provides the called substation A3 with battery current for talkm ne' purposes. W'henthe relay 190' encruizes. thou the armature 185 disenguges from the Contact point 1851, thereby breuking' the circuit through the supervisory lamp 181, which indicates to the operator that the culled subscriber has answered. Similarly, when the rrlny 191 attractsits armature 173 from the Contact point 1747, the circuit tl'iroxlgh the line lamp 172 is broken. even srlter the operator restores the key o to nor um] position. The two substntions A und A being thus Connected, colnnuniication muy then be carried on over the conductors shown in heavy lines in 1 and 2. After #he conversation has terminated, and the rei-civcrs :l and 188 have been restored to their respective. switcl1-hooks. the central oflice appuratus is,'1eleased, and the energizing rircuil through the relays 157. 190 and 191 be nonies broken, whereby their respective :ii-matures return to normal position. The armature 169 engages the Contact point 170, thus closing a circuit through the lamp 198, which circuit extends from ground G1E through the ring 182 and plugl contact 183, hunp 198, Contact point 170, armature 169, :1nd through battery Bto ground G11. The armature 185 upon engaging the Contact point 184 `closes a circuit through the lamp i161, :is previously explained. Also, the arnmture 173 engages the Contact point 1741, but the circuit. through the lamp 172 broken at the contact point 171, the said lamp does not glow. The simul tnneous glowing of the lamps 198 and 181 gives the operator the disconnect signal.

.Suppose that the subscriber at substation A2 alone restores his receiver, and that the subscriber at suhstatlon A remained upon the line, deslrmg another connectlon at the manand unl exchange. ln Ihnt event the line lump lip' undsupervisor- Vlump181 glow, ou ing,r io lhc fart that the relay 157 roinuins energized while thc relnys 1H!) :1nd 191 denrrgize. The circuit through the lump 172 extends from ground l lo the nrrmuure 176, contact point 171, springs 175 and 176, lump 172, contact point 171, armature 169 lo the ha!4 tory ll', thence to ground (ln. The rircuit `for the lump 161 extends from Around (il through the ring v182, plugV eontzu'l 163. lump 161. connu-t point 184, :irnmlurr 1% ol" the relay lil() to the buttery B. und thence lo ground ('i. The glowing oi the lump 17:2` und the hunp 161 indicates thut Ihr suhsrrihrr at suhstntiou -V has restored his revolver. und [hut the subscriber :it substation. A\ mill wf'its upon the trunk-line. desiringr another oonnerliou. The key r is operated. us uhm .L l'o bridge thc opcrnlous set o :ii-ross the truuk (coluluclors 1.3.1 :nul 156. lhrrrlrv the operator muy learn what' couuertion is desired.

'lfhe release of the central ollire switch inn' ui'ilmmltus occurs when the milling sul),A srlihcr hnngs up his 1'erei\'\.r und grounds his rc1-tirol und rotary lim` coruluctors 2f und itl simultaneously. lhercliv producing,r a release of the .switches through the n1cdinni of which the connection was estuh` lished. As the switch-hook 3 descends the release springs 7. 8 and 9 are pressed into contact, whereby the` vertical und rotary line relays 93 und 94; of the connector E are energized, togetheuvith the difl'erential relay 106, in the following.;r manner: The result of grounding the rotary line conductor 30 is to unbalance the differential relay 106 by shunting or short-circuiting the winding 106 between ground G" ut the substation A und the ground GT ut the connector E. The shuntinnv or short-cirtniting branch muy be traced from the subhtution ground 'l' to the ground springs 14; and 15, thence to the releuse springs 7 and. 8 to the rotary line conductor 30, line switch bank springs 57 and 5H, trunk conductor 83, rotary line relay 94, winding 108 of the differential relay 106, back-bridge relay springs 166 and 168 to the side switch Wiper 101 and to ground G7. The differential relay immediate] energizes by the How of current through7 the Winding 107', by reason of the ground connection to the vertical line conductor 29. The inagnetizing current flows from substation ground G to the ground release spring 7, thence through the release springs 8 and 9 to the vertical lii1e'conductor 29, line switch bank springs 55 and 56, conductor 82, connector vertical line relay 93, WindingA 107 125 of the differential relay 106 to the batterv lead 130, and through battery B to ground G. The differential relay 106, upon energizing, separates the springs 164 and 165 and carries the springs 165 and `199 into engage- 130 ment. The former of said Springs (namely the springs 164. and 165), as already explained, nre comprised in t'ho energizing circuit ol the Mok-bridge relay 10S?, so thaty as soon :ls the, said Springs sopnrntle, the said relay 109 rleincrgizes, whereby the spring 166 lenves tho ground spring 1115 :unl returns into engngomont with the nongrounded battery sprinrT 167'. The effect on this lust operation is to remove tho shunt from the differential relay vv'intlino 108, in series with the rotary line` relny 91, as :1l-- rendi' described, estalillishing u ffii-enit; through said rclnly and winding`y whereby n, clurenli-llow is: set up in a reversidirection, further strengthening' th differential relay 10V und rciinergizing the rotnry. line rclny 91. niler these ronclitions the linerclays U3 und 91 are energized, whereby the trunkrelease, Springs 200 und 201 are pressed into Contact While the differential relay Springs 105 :unl 199 are, in engagement, with the resully that :in energizing' circuitr is established through the rcltnsc nn'ignel` D8 of the connector E in series with the buck-release relay LZ allotted to tho tr|inlfline- The hitch relense relny 021 muy he ronsillmml either n pnrt of the connector 1C or :i` imrt or lie, |ritul-linfthnt terzninntu'rin (no line Snitch lmni; spring-s i0 unil 59. ln any wont, the ,ui'pose olI this relai' 72H2 is to pril-ventitho rele-use ol the line switch during); the busyrelensv oi" the connector-Mult is, e'hizn The connector E attempts to close connection u ith :L hns)i line ilA is relensefl; lint contrai- V to the practice heretofore employed, :unl owing to the provision of the said relay 202, null the l'nrt that the. conne'iftm' rrh-nse mug; nelJ has two circuits, the line s'wifeh 1'" is not released h v the busy-release ol: lhe ronnert'or. The release nuignrl` E2G. oi' the wie nel-tor, upon energizing, resin he `su'It'rli nml .switch slin'l't` to nm n, woe

in :t ninnnrr urli-known :intl 'luiii il illcil in wnnr-j'tiim with the ifonnertoi clit-zrlosrrl in .will roniurtoi' ontving 'it uhirh time, fw vom. the liinnml primati nun-rs fill, 5l] unil 9; uriA rlisronnertril troni lhfV ilorinnl romlurlors 152 :lull l-il vnfl the prim-ltr Conlznt. The mtergizing of the lmuli-rllt-nso rilni 202 fzirrios the lmrli-rrleusc relay min-ings Q03 nnntl )ll-l into engnn'ement. entrgrr/:ingr thel releuso muguet lll of' the lino switrh "Q llhen thiA nrnmtlurr. of the release relri'v 7:02 is nliruclctl un energizing' circuit is srt up through the rcltnso ningnll All o1 thel lim` switch (l. when the springs 20? tml :ill-l nre hroug'ht into rontnrt. which energizinto,P rirruil mtl-nils from ground ll" through thtsprings Zll' und 201, ronlluctor Sil. hunk springs G2 nml l, through the release ningm-l ll to t'lnl buttery lend 130, und through lmtleiv l to ,ground (l. When the rrlense, muguet; -ll energizes. the armature 41"l is nt1- trui-tell, whereby the armature 43 of the trip position. ln'mging it ning-net 4l) is raised, compressin r the spring .70, :nul the catch 48 engages t2] Ylil of the plunger arm 3S, remni ing thus in rvmlimss to restore, tho lino switch. As soon ns the substation role-isc springs 7, 8 :unl il supnrnte. the energizing circuits of the rotnrlv und vertical linel relays 93 und fl-l ol" the ronneot-or E nre destroyed. AS :i result. he energizing eil-unit; through the relensr nmgm-t UH unil the bnclorelonst-fV roluy i502 is broken The rlenerzation of the lnnflerclense relay 202 in turn causes the (lrirn-,rgizntion ol. the release magnet 4l. ot` the. line Switch C. W'hen the rolensc insignet` l] of the sait'l line switch clencrgizes, the rctrnrling spring .'30, through the nieflinm of the armatures 48 and 41, with- (l1-:ms the plunger 37 from itis operated into normal engagement with the plunger shaft 52; as n ro Snlt. of course, destroying the. energizing rircuit of ihe cut-off relay 39, removing4 the gum-ling porcntinl from the muster switch heul.v (l intl also Vfrom the connector hunk, :tnfl 'lisronnert'ing' the (failing suhsrrilwrs line #miti-li l'ronl tli'c Coninclm' ll. The, milling subscriber thiny restores all of the switching; apparatus whirl; he originallyY hroughl loro use. 1ly will he geen that the ronneutor switch E muy also he usr-rl to es tuhlish connection heiwcen any' two automatic subscribers ol the same. exchange-wthat` is, two subscribers such as the suhsrriljiers i un" A.' (Fig, l). Such loc-nl romurrtions will, of course. bo confined to the lirsl nino levels in the connector E, und of all conne-k n's sinilarly constructed: for, ns previo) sly Yplnincd, said connerror aulonuitirully rotates to select :my one of n group of trnnlplines on the tenth level. It will he olwious lhnti the nulonnlliiu rornling 'ifiljun i'i :any instance, neen' not` ho row ,i' ed to ilse tenth. len-l.J but muy hc usi-d in my lrwl in which if, may he l'mrrnl il sit-uhh le the case of the minimi-fir E, fel' roiuwm Ehi z'intioniiiir rotating; f'enlurc fails tu :.:Nieur in :my ol.' the First nino levels. Wherefore, he subscrilwr :il substation A (Vip. l). to wall the, sohmriber at stilistan tion :l operntcs the flial in t e manner :ilN runvlff tlcsorilntl. 'lll-.C lille swili'll (l iS opor nien". :is previously explained, to seize the, trunl; romilu'tors 82 :ind 83. The first digit hein; L. the vertical line relay of the eonfir-tor is energized twice, and the Shaft wipers nre advanced two steps. Then the rot-(ujf line is grounded the rotary line relay operates to energize the private magnet, whereby the side switch passes from first to second position. The lust digit being nuu ht the vertical lincconductor 29 is groumed ten times, thereby operating the vertical line relay, which relay in turn causes the energizntion ot the rotary magnet 96 and the step-hystep rotation of the shaft wipers,

terminal The energizing circuit tary magnet extends through the springs 138 through the said rofrom ground G und 137, conductor 139, springs 140 and lll. side switch wiper -through battery- B to ground (l. The rotary nmgnet 96 being; energized Ien limes, the shaft 89 is rotated ten steps, whereby the Wipers 90, 91. and 92 :ire carried into engagement. with the tenth ternnnnl of the seeoncl level, 'from which level lead the nor` mal conductors 212, 213 und 214 whirh extend to the line switch C of the culled line., and he former two of which comlive-.tors continue through to the called subst-.ation #20. After the connector has thus operated, the ground impulse to the rotary line conductor 30 energizes the rotfiry line relay 94 of the connector over circuits that are already known, which relay in turn operates the private nnignrt 9i'. wherehv the side switch is released from second to third posiVl tion. The culling s1itvse1'iliei"'=z line [fondue tors 29 and 30 are now extended to the called line conductors 215 und S210, und con* Tersution may he carried on over the ein cuits shown in heavy lines7 Fig. 1. Vllhen the milling suhsitriher :il` substation A. restores his receiver to the switelbliooli, the release of the central office switching appnratus is brought about, as previousl)r eX- plained. t; will be evident, of course, that when the connector side switch posses to third position to extend the calling subscribers line to the line conductors und E216, n guarding potential is established nt the private wiper 92, as previously este plained, tor protecting this seized line. This guarding potential, furthermore. torens :in energizing torrent through. the bridgeentofi' relug' 22].. whereby the said relu),r only energize to separate the Vloriiig ,7reelxi", oit' relay springs 2522, und 255i, in order to remore the norinul shfut-eireui; maintained throughsuid springs from across the relied line, to eil-.diie the subscribers to ffoigmunicale. Had the subseriber A been busy. the connector private henk contarte rorrespond ing to said line would have been grounded, and the private wiper 92 would have heen arriecl into Conner-tion 'with said grounded contant. rThe connector snitrh lil theo., upon attempting to close the eonneetiou between the calling; :ind Called line. would have heen autoinatiezilly released. The operation ot' this guarding potential to cause the busvrelense oii'the connector Eunny he described :is follows; After the privelley wiper z ilus heen carried onto the grounded Contact. as aforesaid, and while the Connector side switch is in second position. then when the rotary line Vrelay 94 is energized at the in stent that the last ground iinpillse is flelivered to the rotary line conductor 3f) the course, seid rotary line rehiy 94', upon enerA gluing, senses the i'n'ivzrl'e. muguet 97 to energize, which magnet then presses the springs 22o und ".226 into contact, at which instant the. energizing; circuit for the, release muguet 95u is eonipleted. This energizing circuit extends from the grounded private rontriet point to the private Wiper 92, thence to the side switeh wiper 10i, Contact point 219, springs 147 und 11S, conductor 227, through the private springs 226 und 225 to the release n'mgnet 98, thence throughthe back-.release relay springs 199 and 165 to the buttery lead l--O, ground G. It will also he understood that the ,lilt'erentiel relay 106 energized at the seme tin'nj'u, owing' to the ground, impulse delivered to the rotary line' conductor 30. HWhen the release magnet energizes it :Lttrrirts its urinuture und forces the support troni under the 'iteh shaft 89, und the side switch to first position. The switeh shaft else drops to nerlnul position, as is Well known lt will he seen, therefore, that only the connector switch E is released, :md 'that the line switch @j rem-sins connected with the eouneetor E. Therefore, when the subscriber his signaling button und thereby grounds his vertical line con duetor 29. the connector switch shaft. is raised, whereby the springs 118 and 117 are pernrilted to close in. 'outuet to close e busysignaling circuit. VFor notifying the calling subscriber that the desired line is busy. This busi Asiglun'dini; eireuit, extends 'from the seeonfilsrp Winding il@ ol' the husyeoil .l (Fig. il through the. :sfrings il? und '11S to the side switch wiper 1.00 tin-nee to the wmlenser lili?, 'through the suhstntion und hoek tiirougli the ferrie-.1l fine relay 9i) to the hnltery' lend llO, und tinck to File Coil lli?. The suhsfn'iher, upon. hearing the liusjosigvnul,` will hung up .his receiver 6find ground his line conductors 9!) und S) siimlinnernislly, causing the release el all ol the switches in the nmnner :ilready explained.

lVith the :U'rzzngement shown it will he evident that the manual subscriber A? muy, if he flesh-ls.` obtain. connection with one of the uutonnitie suhserihem` ot' the automatic exehunge---suseriher A." (No. Q0), for example. ln order to eXplain the method by nhieh this eonnertion muy be established, und in order to ineke the. illustration as simple :is possible, it will be assumed that the conductors l5!) and 156 of Fig. Q terminate in the line switch (l. (')fcourse, for the time l)eingr it will he assumed that' the conductors .59 und 30 are disconnected there `from. ln thut event, when the receiver 18S is removed from the switch-hooi; 189 a sigund through battery B to leo l vl il nal appears at the line lamp Q05. The operator inserts the plug p into the jack J and operates the'key e to bridge the operators set o across 'the extended line, and after learnin that substation' iA, for instance, which 1s allotted to the line 50, is desired, the operator throws the key e in the opposite direction, whereby the springs 160 and 163 disengage' from the springs 161 and 162 and pass into enga ement with the springs 206 and Q07. By t is operation, when the said springs 160 and 161 and the springs 1.62 and 163 disengage, the calling substation A2 and part of the cord circuit are disconnected from the trunk-line conductors 155 and 156. Furthermore, when the springs 160 and 206 and the springs 1.63 and 207 engage, the operators calling device d is bridged across the trnnkeline conductors instead. To call the number 50, which it is assumed is the number o1 substation A, the operator presses the button 208 onto the ground spring 209, whereby a preliminary impulse is sent over the rotary line conductor 156 for operating the line switch allotted to the trunkdine conductors 155 and 156, and the calling de vice is then operated in the usual manner to call the number 50. After the operator has signaled the called subscriber at A the key e is restored to normal position, whereby the springs 160, 161.1aud 162, 163 engage, thus extending the calling subscribers line conductors 186 and 187 to the trnlcline condoctors 155 and 156 over the circuits indicated by the heavy lines in Fig. 2. The relays 15T, 190 and 191, upon becoming ener- ,gized by the talking battery current, attract their respective armatures, breaking the oircuits through the supervisory lamps, as before explained. Then the subscribers A2 and A restore their respective receivers to the switclrhooks 'the circuits through the relays 1Q() and 191 become broken, whereby the armatures return to normal position. The armature 185 engages the contact point 184, whereby the circuit through the supervisory lamp 181 is completed, as before explained. Furthermore, since the talking battery current has been removed from the line romluctors 155 and 156, the relay 157 also deincrgizes, and the armature 169 en` gages the contact point 170, whereby the vir-cuit through the lainp 198 is completed. Th1l ianips 181. and 198 glowing simultane- 5: ously give the operator the disconnect signal. and accordingly the springs 208 and 210 are pressed simultaneously onto the ground spring4 20), whereby both the vertical and rotary line conductors 155 and 156 are grounded simultaneously, thus bringing annui the release of the central oliice switches. in the Well-known manner.

As indicated in Fig. 2, not only can the manual subscribers be called by the automatic subscribers, and the manual subscribers call the automatic subscribers, but also one manual subscriber can call another manual subscriber by the use of the cord circuit K, of any suitable or approved design, in the ordinary manner.,

Fromthe foregoing it will be seen that I provide a telephone exchange system in which provision is` made for automatic service between the subscribers of a branch exchange or sub-central station, as well as for eifieient service between the subscribers oi the two exchanges. The subscribers at the main exchange can carry on communication between themselves in any suitable manner, as, for example, by means of the manual apparatus shown in Fig. 2,*or by automatic apparatus if desired. In any event, however, the connectors at the branch eX- change shown in F ig. 1 are adapted for two kinds of service-that is to say, each connector is adapted not only to make the final connections directly with any called subscribers lilies that terminate at thc branch exchange, but is also adapted, when raised to a certain level, to operate automatically, and in the manner of a selector, for automatically selecting an idle trunk line leading to the main exchange or central station. Means are provided, as described, for automatically converting each connector into an automatic trunk-selecting mechanism as soon as it is raised to a certain level, so that the selection of the idle trunk is purely automatic. Although the trunks leading from the non-numerical line or individual switches of the branch exchangey are connected directly to the connectors, it is possible for each connector to automatically release and restore itself to normal condition, after having tried to seize a busy subscrihcrs line, without releasing the line switch of the calling subscriber. In this way a comparatively small number of subscribers can be grouped together to torni or compose a branch exchange, with eicient service between all of the subscribers thereof, and the sa'me apparatus which furnishes this service is also adapted to give automatic trunking service to the main exchange. .Any trunking connections of this kind are efficiently supervised by the opera.- ors of the manual board at the main exchange, through the medium of the supervisory apparatus associated with the trunking operators coni-circuits, in the manner explained. Furthermore, it will be seen that these connectors which have provisions for operating automatically as trunk-selectors are adapted to control the supply of talking current to the calling subscriber, and also to the called subscriber, if the latter be found in the same exchange; but when the call is over a trunk-line to the main eX- change` then the battery current flowing through the connector in the direction of the the other exchange. At the main exchange the said trunk-lines terminate in trunking operators cord-circuits of the kind shown in Fig. 2, and at the branch exchange these trunk-lines `terminate in non-numerical trunking switchesl ofthe kind shown at C in Fig. l, as well ,as in the multiple contacts or terminals of automatic connectors Voi" the kind shown at E inL Fig-f1. In this way the automatic subscribers-j` at theV branch exchange" cany use thesa'id trunk-lines for automatically trunking to the main exchange,

andthe operators at the said main lexchange can use the same trunk-lines vfor trunking to the branch exchange and for then automatically trunking to the lines of the called subscribers. When the connection is be tween subscribers of the branch exchange, then the current from the battery B is supplied in opposite directions for talking purioses, as Well as for releasing purposes.

hen the connection is between the subi scriber of one exchange and the subscriber of another'exchange, then the current from the, battery B iows over the line of the branch exchange subscribers line for both talking and re easing purposes, and in the opposite direction over the trunk-line for supervisory purposes only; the current for talkin purposes being supplied to the manual su scriber from the battery B in the manner explained. i

It will also be seen from the foregoing that when the connector switch E is acting altogether under the directive control of the calling subscriber, as for example when the subscriber A is calling the subscriber A', both ofthe motors 95 and 96 are subject at one instance to the direct control of the calling subscriber A, whereas when the `switch E is acting as a rotary connector only one of the motors is subject to the di rect control of the calling subscriber, to Iwit,

the motor 95, or the vertical magnet.

What I ,claim as myinvention is :lv

1. In atelephcne system, a bank of terminals, subscribers lines ,leading rom one or more of the levelsof said bank of terminals, trunk-lines leadin from at least one of the levels of said ank of terminals, switch wipers adapted to engage said termi` nals,l two motors both subject at one instance to the direct control of the calling subscriber for causing said wipers to seize A thc terminal of any idle subscribers line,

and only one, at another instance, subject to the direct control of the calling subscriber, for causing said wipers to pass terminals f busy trunk-lines 'and stop on the terminal of the first idle trunk-line when a trunking connection is desired.

2. In a telephone s stem, a connector provided with a bank o terminals arranged in a .plurality of levels, subscribers lines leading from one or more of said levels, trunle lines leading -from at least one of said levels, and automatic means comprising .two motors for causing said connector to select idle trunk-lines or to connect with any one of said subscribers lines, only one 8o of said motors under ythe direct control of the calling subscriber to iind an Vidle trunk line and both of said motors under the con,- trol of the calling subscriber to connect with one of the subscribers lines, and a calling line for'controlling the connector. 3. In a telephone system, an automatic switch provided with a bank of terminals `aziranged in a plurality of levels, suitable lines leading from said terminals, said switch having provisions for enabling 4it to seize any particular line desired by the calling subscriber in one or `more of the levels thereof, and having provisions for automatically selecting the first idleline in at least one of said levels, said first provisions comprising two motors under the direct control of the calling line and said last provisions comprising onl one motor under the direct control of t e calling line, and a calling line for controlling the automatic switch.

4. In a telephone system, a main exchange and a sub-exchange, trunk-lines extending from one exchange to the other, and connectors at the sub-exchange, each connector having provisions for seizing any particular one of a number of subscribers lines terminating thereat, and each con` nector having also provisions for automatically selecting idle trunk-lines leading to the main exchange, said first` provisions nlcomprising two motors under the direct control of the calling line and said last provisions comprising onl one motor under the direct control of t e calling line, and callin lines for controlling the connectors.

5.1gn a telephone system, a main exchange and a branch exchange, trunk-lines leading from one exchange to the other, connectors in the banks of which the trunklinesA terminate at the branch exchange, means individual to eachconnector for completing the connection of said connector with an idle trunk line by the calling of 2.125 single digit, and subscribers lines also ter? minating directly in and adapted to be seized by said connectors.

6. In a telephone system, a main exchange and a branch exchange, trunk-lines .any particular connecting one exchange with the other, automatic connectors in the banks olE which the trunk-lines termin-atc at the branch exchange, means individual to each connector for completing the connection of said connector with an idle trunk line by the calling of a single digit, a local trunk for and lead ing to each connector, an automatic trunking switch for and in which each local trunk-line terminates at the branch exchange, subscribers lines also terminating in and adapted to be seized by said connectors, and means for controlling said trunking switches over the trunk-lines to cause the trunking switches to select the trunks of idle connectors when subscribers of the main exchange call subscribers of the branch exchange.

T. In a telephone system, a main exchange and a branch exchange, trunkslines connecting one exchange to the other, auto matic 'connectors in the banks of which the trunkslines terminate i' one exchange, means individual to enel. connector' for completing the connection of said connector with an idle trunk line by the calling of a single digit, a manual switchboard in which the trunk-lines terminte in the other exchange, subscribers lines terminating directly at. said manual switchboard, means on the manual board for connection with the lines terminating thereat, and other subscribers lines terminatin directly in and adapted to be seized by said connectors.

8. In a telephone system, a connector provided with a bank of terminals arranged in a plurality of levels, subscribers lines leading from one or more of said levels, trunklines leading from at least one of said levels, automatic means comprising tivo motors for causing said connector to select idle trunklines, or to connect with any one of said subscribers lilies, only one of said motors under the direct control of the calling subscriber*-4 to find an idle trunk line, both of said motors under the control of a calling subscriber to connect with one of the subscribers lines, a calling line for controllin the connector; and a centralized means o current-supply for furnishing talking current through said connector to calling and called subscribers lines. l

9. ln a telephone system. an automatic switch provided with a bank of terminals arranged in a plurality of levels7 suitable lines leading from said terminals, said switch having provisionsi for enabling it to seize line desired by the calling or more of the levels the-reof. and having provisions for automatically selecting the first idle line in. at least one of said levels. said first provisionscomprising two motors under the direct control of the calling line, said last provisions conqirising only one motor under the direct control ot subscriber in one the calling line, a calling line for controllinO the automatic switch and a centralize means of currcntsupply for furnishing talking current through said automatic switch to calling and called subscribers lines.

l0. In a telephone system, a main cx change and a sulrcxchange, trunk-lines` extending from one exchange to the other, conm ncctors al the subaixehange, each connector having provisions for seizing any partici lar one of a number of subscribers lines terminating thereat, and each connector having also provisions for automatically selecting idle trunk-lines leading to the main exchange, said first provisions comprising two motors under the direct control of the calling line, said last provisions comprising only one motor under the direct control of the calling line, calling lines for controlling the connectors, and a centralized means of current-supply for furnishing talking current through said connectors to calling and called subscribers lines,

l1. ln a telephone system, a main ex change and a branch exchange, trunk-lines leading from one exchange to the other, connectors in the banks of which the trunklines terminate at the branch exchange, means individual t0 each connector for completing the connection of said connector with an idle trunk line by the calling of a single digit, subscribers lines also terminating directly in and adapted to be seized by said connectors, and a centralized means of cui rent-supply for furnishing talking current through said connectors to calling and called subscribers lines.

12. In a telephone system, a main exchange and a branch exchange, trunk-lines connecting one exchange with the other, automatic connectors in the banks of which the trunk-lines terminate at the branch exchange, means individual to each connector tor completingi the connection of said connector with an idle trunk line by the calling of a single digit, a local trunk for and lead ing to each connector, an automatic trunking switch for and in which each trunk-line terminates at the branch exchange, subscribers lines also terminating in and adapted to be seized by said connectors, means for controlling said trunking switches over the trunk-lines to cause the trunking switches to select the trunks ofcidle connectors when subscribers of the main exchange call subscribers of the branch exchange, and a centralized means of currenbsupply for furnishing talking current through said connectors to calling and called subscribers lines.

13. In a telephone system, a main exchange and a branch exchange, trunk-lines connecting one exchange to the other, automatic connectors in the banks of which the trunk-lines terminate in one exchange, means individual to each connectorfor completing the connection with an idle trunk line by the calling of' a single digit, a manual switchboard in which the trunk-lines terminate in the other exchange, subscribers lilies terminating direct-ly at saidmanual switchboard, means on said manual board for connection With the lines terminating thereat, other subscribers lines terminatin directly in and adapted to be seized by said connectors, and a centralized means of current-supply for furnishing talking current through said connectors to callin and called subscribersJ lines.

14. n an automatic and manual telephone system, a connector provided with a bank of terminals arranged in a plurality of levels, subscribers lines leading from one or more of said levels,'trunklines leading from at least one of said levels, automatic means for causing said connector to select idle trunk-lines, and a centralized means of current-supply for furnishing talking current through said connector to calling automatic subscribers lines, adapted to supply current in the direction of a called manual subscriber for supervisory purposes.

15. In an automatic and manual telephone system, an `automatic switch'provided. with a bank of terminals arranged in a plurality of levels, suitable lines leading from said terminals, said switch having provisions for enabling it to seize any particular line desired b the calling subscriber in one or more of t e levels thereof, and having provisions for automatically selecting the lirst idle line in at least one of said levels, and a centralized means of current-supply for furnishing talking current through said automatic ,switch to calling automatic subscribers lines, adapted to supply current in the direction of a called manual subscriber for supervisory urposes.

16. In a telep one system, au automatic and manual main exchange and a sub-exchange, trunk-lines extending `from one exchange to the other, connectors at the subexchange, each connector having provisions for seizing any particular one of a number of subscribers lines terminating thereat, and each connector being also provided with means for automatically selectin idle trunk-lines leading to the main exc ange, and a centralized means of current-supply for furnishing talking current through said connectors to calling automatic subscribers lines, ada ted to supply current in the direction o a called manual subscriber for supervisory purposes.

17. In a telephone system, a main exchange and a branch. exchange, trunk-lines leading from one exchange to the other, means at 'the main exchange for connection of said connectorV with said trunk-lines, connectors in the banks of which the trunk-lines terminate' at the branch exchange, subscribers lines also` terminating directly in and adapted to be seized by said connectors, a centralized means of current-supply for furnishing talking current through said connectors to calling subscribers lines, and adapted to supply current in the direction of a called subscriber in the main exchange for supervisory purposes.

ln a telephone system, a main exchange and a branch exchange, trunk-lines connecting one exchange with the other, means at the main exchange for connection with said trunk-lines, automatic connectors in the banks of which the trunk-lines terminate at the branch exchange, a local trunk for and leading to each connector, an automatic trunking switch for and in which each trunk-line terminates at the branch exchange, subscribers lines also terminating in and adapted to be seized by said connectors, means for controlling said trunking switches over the trunk-lines to cause the trunking switches to select the trunks of idle connectors when subscribers of the main exchange call subscribers of the branch exchange, a centralized means of current-supply lor furnishing talking current through said connectors to calling subscribers lines, and adapted to supply current in the direction of a culled subscriber in the main exchange for supervisory purposes.

19. In a telephone system, a mai exchange and a branch exchange, trunk-lines connecting one exchange to the other, means at the main exchange for connection With said trunk-lines, automatic coimectors inf the banks of which the trunk-lines terminate in one exchange, a manual switch-board in which the trunk-lines terminate in the other exchange, subscribers lines terminatingv directly at said manual switchboard, other subscribers lines terminating directly in and adapted to be seized by said connectors, and a centralized means of current-supply for furnishing talking current through said connectors to calling subscribers lines, adapted to supply current in the direction of a called manual subscriber for supervisory purposes.

20. In an automatic and manual telephone system, a connector provided with a bank of terminals arranged in a plurality of levels, subscribers lines leadin from one or more of said levels, trunk-hnes leading Jfrom at least one of said levels, automatic means for causing said connector to select idle trunk-lines, a centralized means of current-supply for furnishing talking current through the said connector to calling a 'tomatic subscribers lines, and a separate or independent source of electrical currentsupply for furnishingr talking current to called manual subscribers lines.

ill. In an automatic and manual telephone system, an automatic switch provided With a bank of terminals arranged. in a plurality of levelsV` suitable lines leadingl from Said terminals.y said switch havingr provisions tor enabliimF it to seize any particular line desired h v the callinr subscriber in one or more ot the levels tliereo'f, and having,F provisions for aiitomatie-all)Y :selectinga the first 'idle line in at least one of said levels, a centralized means of current-supply tor furnishing talking current through the said auton'iatic switch to calling automatic sub .si-ribera lines` and a separate or independenty source of electrical clu'rentesupply for furnishing talking current to called manual subscribers` lines.

*32. In a teleilhone system, an automatic and manual main exchange and a Sub-exchange, trunk-lines extending; from one exchange to the other, connectors at the suhexchange. ear-h count-rter having` provisions for laeining anv particular one, oti a number of subscribers lines terminal ingr thereat, and each connector being also provided with means t'or automatically selecting idle trunklines leading to the main exchange, a eentralized means of currenbsupply for lurnishiug talking current through the Said connectors to calling automatic subscribers lines, and a separate or independent source of electrical current.-suppl)y for Jfurnishing talking current. to called manual subscribers lines.

23. In a telephone system, a main exchange and a branch exchange, trunk-lines leading from one exchange to the otherg means at the main exchange for connection with said trunk-lines, connectors in the banks of which the. trunk-lines terminate at the branch exchange, subscribers lines also terniimiting directly in and adapted to be seized by said eonriccinrs.y a centralized means of current-supply for i'urniehinfjr talle innV current through the said connectors to calling: suliscribers` lines, and a separate or independent source, of electrical currentfsnppli` l'nr furnishing talking current to called manual subscribers lilies.

2l. lu a telephone system, a main exchange and a branch exchange, trunk-lines connecting one exchange with the other1 nir-ans at the main exchange for connection with said trunk-lines, automatic connectors in lille banks of which the trunlclines terminate at the branch exchange, a local trunk foi" and leading,r to each connector, an auto matic trunking switch for and in whichveach trunk-line terminates at the branch exchange, subscrilwrs lines also terminatingr in and adapted to be seized by said connectors, means Jfor controlling said lrnnking switches over the trunk-lines to canse the trunkiner switches to select the trunks of idle connee ters when subscribers of the main exchange call snl'iseribers o't` the branch exchange, a eentrz'slized means of currentsnpply for fui nishing talking current through the said connectors to calling subscribers lines` and a separate or iudelendent source ot' electrical current-supply for furnishing talking current to called subscribers`r lines in the main exchange.

25. In a telephone system, a main exchange and a branch exchange, trunk-.lines connecting one exchange to the other, means at the main exchange for connection. with said trunk-lines, autcniatic connectors in the. banks ot' which the trunk-lines terminate in one exchange, a manual s\\`itchboard in which the trunk-lines terminate in the other exchange, subscribers lines terminating directl)Y at said manual s\.'itchboard other subscribe-rs7 lines terminating directltir in and adapted to he eti-ized by said conne'torsj a centralized means ot' currtintsupply ter iurnishing talking current through the said con nectnrs tn calling subscribers lines` and a separate or independent :source of electrical current-supply for furnishingsl,r talking cui rent to called manual subscribers lines.

26. ln a, telephone system. a connector provided with a bank of terminals arranged in a plu ality of levels. subscribers lines leading from one or more of said levels, trunklines leading from at least one of said levels, automatic means for causing said connector to select an idle trunk-line by the calling of a single digit` and a trunking operators snpervieorj,Y mechanism for supervising any trunking connection established by the con nectar.

QT. In a telephone system, an automatic switch provided with a bank of terminals arranged in a pluralityY of levels. suitable ,lines leading from said terminale,y suidnwiich having provisions for enabling it to seize any particular line` desired by the calling subscriber in one or more of the levels thereof. and having provisions for auto matically selecting the irst idle line in at least. one of said levels by the calling of a single digit7 and a trnnking operators supervisory mechanism for supervising any trunking eonnectinn established by the' automatic switch.

28. In a telephone system, a main exchange and a sub-exchange, trunk-lines extending from one exchange to the other, connectors at the sub-exchange, each connector having provisions for seizing any particular one of a number of subscribers lines terminating thereat; and each conneeM tor being also provided with means for automatically selecting idh` trunk-lines leading te the main exchange by the calling of a with said trunk-lines, connectors in the banks of which the trunk-lines terminate at the branch exchange, means individual to each connector for completing the connection of said connector with an idle trunk line by the calling of a single digit, sub-V scribers lines also terminating directly in and adapted to be seized by said connectors,

' and a trunking operators supervisory mechanism for supervising any trunking connection established by a connector.

30. In a telephone system, a main exchange and a branch exchange, trunk-lines connecting one exchange with the other, means at the main exchange for connection with said trunk-lines, automatic connectors in the banks of which the trunk-lines terminate at the branch exchange, means individual to each connector for completing the connection of Said connector with an idle trunk line by the calling of a single digit, a local trunk for and leading to each connector, an automatic trunking switch for and in which each trunk-line terminates at the branch exchange, subscribers lines also terminating in and adapted to be seized by said connectors,rmeans for controlling said trunkin switches over the trunk-lines to cause t e trunking switches to select the trunks of idle connectors when subscribers of the main exchange call subscribers of the branch exchange, and a trunking operators supervisory mechanism for supervising any trunking connection established by a connectar.

31. In a telephone system, a main ex `change and a branch exchange. trunk-lines connecting one exchange to the other, means at the main exchange for connection with said trunk-lines, automatic connectors in the banks of which the trunk-lines terminate in one exchange, means individual to each connector for completing the connection of said connector with an idle trunk line by the calling of a single digit, a manual switchboard in which the trunk-lines terminate in the other exchange, subscribers lines terminating directly at said manual switchboard, other subscribers lines terminatin directly in and adapted to be seized by said connectors, and a trunking operators supervisory mechanism for supervising any trunking connection established by a connector. Y

3Q. In a telephone system, a connector provided with a bank of terminals arranged in a plurality of levels, subscribers lines leadin from one or more of said levels, trunkines leading from at least one of said levels, automatic means for causing said connector to select an idle trunk-line by thc callin ot asingle digit, and a manual swilchoard opcrators mechanism vfor controlling said connector When said trunklines are used by the operator for calling subscribers lilies terminating in said connector. f

33. In atelephone system, an automatic switch provided with a bank-of terminals arranged in a plurality of levels, suitable lines leading from said terminals, said switch, having provisions for enabling it to seize any particular line desired by the call ing subscriber in one or more of the levels thereof, and having provisions for automatically selectin the first idle line in at least one of said levels by the calling of a single digit, and a manual switchboard operators mechanism` for controlling said automatic switch when said lines are used by the operator for calling subscribers lines terminating in said automatic switch.

34. In a telephone system,'a main exchange and a sub-exchange, trunk-lines extending 'rom one exchange to the other, connectors at the sub-exchange, each connector having provisions for scizin any particular one of a number of subscri ers lmcs terminating thereat, and cach connector be- 'infr also provided with means for automatically selecting idle trunk-lines leading to the main exchange by the calling of a single digit, and a manual"switchboard operators mechanism for controlling said connectors when said trunk-lines are used by the operator for calling subscribers lines terminating in said connectors.

35. In a telephone system, a main exchange ,and a branch exchange, trunk-lines leading from one exchange to the other, connectors in the `banks of which the trunklincs terminate at the branch exchange, means individual to each connector for completing the connection of said connector with an idle trunk line by the calling of a single digit, subscribers lines also terminating irectly in and adapted to be seized by said connectors, and a manual switchboard op? 

